2 - 10,000 RPM meter

[glens5]

Accurate high resolution RPM meter using TTL CMOS I.C.'s
No micro-controller to program. The few I've tried had poor resolution below a couple hundred RPM. Bright LED display with a pot for fine adjustment.
I used this on the old horizontal mill I'd converted.
The magnets are Chinese neodymium from E-bay and only cost a few bucks. The large number of magnets are necessary for the resolution at very low RPM
This is my own design and seems to work just fine and I'm sure could be used in other applications.

[DIYer]

Thanks glens5! We've added your Tachometer to our Electronics category,
as well as to your builder page: glens5's Homemade Tools. Your receipt:

Tachometer by glens5

tags: LED, tach, electronics

[Christophe Mineau]

Hi,
Could you develop why You needed so much magnets? It looks like being a little bit over engineered for a simple spindle speed indicator?
360 divided by 40 is 9degree angular resolution, it would be nice for low low speeds, like a few rounds per minute, but for a mill ?

[glens5]

I had developed it for another application but it did work well for the mill.
But like I said, it will work well in other applications.

[Drew1966]

Glens5, you’re doing some very nice work there.